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https://doi.org/10.5194/egusphere-2023-2802
https://doi.org/10.5194/egusphere-2023-2802
05 Dec 2023
 | 05 Dec 2023

Rate coefficients for the reactions of OH radical with C3-C11 alkanes determined by the relative rate technique

Yanyan Xin, Xiaoxiu Lun, Shuyang Xie, Junfeng Liu, Chengtang Liu, and Yujing Mu

Abstract. Rate coefficients for the reactions of OH radicals with C3-C11 alkanes were determined using the multivariate relative rate technique in various bath gases (N2, Air, O2). A total of 25 relative rate coefficients at room temperature and 24 Arrhenius expressions in the temperature range of 273–323 K were obtained. Notably, a new room temperature relative rate constant for 3-methylheptane that had not been previously reported were determined, and the obtained KOH values (in units of 10-12 cm3·molecule-1·s-1) in different bath gases were N2, 7.90±0.25; Air, 7.93±0.33; and O2, 7.36±0.11. Interestingly, whilst results for n-alkanes agreed well with available structure activity relationship (SAR) calculations, the three cyclo-alkanes and two trimethylpentane were found to be less reactive than predicted by SAR. Conversely, the SAR estimate for 2,3-dimethylbutane were approximately 22 % lower than the experimental value, highlighting that the limited understanding of the oxidation chemistry of these compounds. Arrhenius expressions (in units of cm3·molecule-1·s-1) for the reactions of various cyclo- and branched alkanes with OH were determined for the first time: methylcyclopentane, (1.62±0.14)×10-11exp [-(256±25)/T]; 2-methylhexane, (1.22±0.04)×10-11exp [-(206±9)/T]; 3-methylhexane, (2.27±0.31)×10-11exp [-(559±42)/T; 2-methylheptane, (1.62±0.37)×10-11exp [-(265±70)/T, and 3-methylheptane, (3.54±0.45)×10-11exp [-(374±49)/T]. In addition, the rate coefficients for the 24 previous studied OH + alkanes reactions in different bath gases were consistent with existing literature values, demonstrating the reliability and efficiency of this method for simultaneous investigation of gas-phase reaction kinetics.

Yanyan Xin, Xiaoxiu Lun, Shuyang Xie, Junfeng Liu, Chengtang Liu, and Yujing Mu

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-2802', Anonymous Referee #1, 22 Dec 2023
  • RC2: 'Comment on egusphere-2023-2802', Anonymous Referee #2, 09 Jan 2024
  • RC3: 'Comment on egusphere-2023-2802', Anonymous Referee #3, 16 Jan 2024
Yanyan Xin, Xiaoxiu Lun, Shuyang Xie, Junfeng Liu, Chengtang Liu, and Yujing Mu
Yanyan Xin, Xiaoxiu Lun, Shuyang Xie, Junfeng Liu, Chengtang Liu, and Yujing Mu

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Short summary
The relative rate constants of OH radicals with C3-C11 alkanes under different bath gases (N2, Air, O2) were obtained, and multiple comparisons were made with previous literature and estimated values, expanding the existing database. The measured relative rate constants of air gases were found to be highly consistent with values obtained in N2, suggesting that the rate constants obtained in this experiment can reasonably represent the rate constants in the actual atmosphere.